IEEE 802.11 communication utilizing carrier specific interference mitigation

ABSTRACT

Wireless communication under IEEE 802.11 standards utilizing carrier specific interference mitigation where an AP or UE employs an ultra-wideband tuner to evaluate available spectrum between several communication bands. Rather than being constrained to communicate in a single communication band, the AP and UEs may utilize more than one communication band to communicate with one another. In doing so, the AP and UE search across several bands and measure interference on a carrier-by-carrier basis across those bands. Either of the AP and UE may select a cluster of carriers for communication, where the cluster of carriers may comprise 1) contiguous carriers in a single sub-channel, 2) contiguous carriers spanning across more than one sub-channel, 3) discontinuous carriers in a single sub-channel, or 4) discontinuous carriers spanning across more than one sub-channel. The mapping between a cluster and its carriers can be fixed or reconfigurable.

BACKGROUND OF THE DISCLOSURE

Wireless communication utilizing bands operated under the IEEE 802.11standards has become increasingly popular. The IEEE 802.11 standardstypically utilize the 2.4 GHz and/or the 5 GHz bands. Because thesecommunication bands are of limited bandwidth, the increase in use oftenresults in particularly high interference levels. To alleviate problemsassociated with high interference, some standards provide for utilizingmore bandwidth. For example, the IEEE 802.11ac standard (which currentlyutilizes the 5 GHz band) is expected to provide a throughput on theorder of 1 gigabit per second by utilizing channels of wider bandwidth,i.e., a bandwidth of up to 160 MHz, which itself may be divided into,e.g., eight (8) 20 MHz sub-channels, four (4) 40 MHz sub-channels, ortwo (2) 80 MHz sub-channels. Future standards are expected to increasechannel bandwidth even more. For example, a proposed future IEEE802.11ac standard utilizes both the 2.4 GHz and 5 GHz bands. Also, theproposed IEEE 802.11ad standard additionally utilizes the 60 GHz band.

Devices operating under the IEEE 802.11 standards may increase datathroughput by aggregating one or more of the available sub-channels forsimultaneous use in transmitting and receiving data. However, even inthe most discrete case, the devices are able to utilize two or moreadjacent or contiguous 20 MHz sub-channels for communication, but areconstrained to utilize subcarriers only within the availablesub-channels. To fully utilize available spectrum, an IEEE 802.11 deviceshould be able to utilize carriers across multiple sub-channels, evenacross disjointed bands (e.g., 2.4 GHz, 5 GHz, and or 60 GHz bands),without regard to whether those carriers are within an otherwiseunavailable sub-channel.

SUMMARY OF THE DISCLOSURE

According to an aspect of the present disclosure, an IEEE 802.11 deviceis implemented within a network to utilize available carriers forcommunication over more than one communication band. Doing so takesadvantage of a wider range of available spectrum and, as a result,increases network efficiency and overall data throughput. A method forwireless communication in a multi-band, multi-carrier wireless network,includes searching across more than one communication band to determineinterference levels in each of the communication bands. The method alsoincludes, based on the determination of interference levels in each ofthe communication bands, identifying candidate carriers in each of thebands for communication. The method further includes mitigatinginterference on a carrier-by-carrier basis for at least some of theidentified candidate carriers in each of the communication bands.Finally the method includes transmitting wireless data on the carriersin each of the communication bands utilizing mitigation interference.

In another aspect of the present disclosure, an apparatus configured forIEEE 802.11 wireless communication includes at least one processor and amemory coupled to the at least one processor. The processor isconfigured to search across more than one communication band todetermine interference levels in each of the communication bands. Theprocessor is further configured to, based on the determination ofinterference levels in each of the communication bands, identify a setof candidate carriers in each of the bands for communication. Theprocessor is further configured to mitigate interference on acarrier-by-carrier basis for at least some of the identified candidatecarriers in each of the more than one communication bands. Finally, theprocessor is further configured to transmit wireless data on thecarriers in each of the communication bands utilizing mitigationinterference.

The foregoing has outlined rather broadly the features and technicaladvantages of the present disclosure in order that the detaileddescription of the disclosure that follows may be better understood.Additional features and advantages of the disclosure will be describedhereinafter which form the subject of the claims of the disclosure. Itshould be appreciated by those skilled in the art that the conceptionand specific aspect disclosed may be readily utilized as a basis formodifying or designing other structures for carrying out the samepurposes of the present disclosure. It should also be realized by thoseskilled in the art that such equivalent constructions do not depart fromthe spirit and scope of the disclosure as set forth in the appendedclaims. The novel features which are believed to be characteristic ofthe disclosure, both as to its organization and method of operation,together with further objects and advantages will be better understoodfrom the following description when considered in connection with theaccompanying figures. It is to be expressly understood, however, thateach of the figures is provided for the purpose of illustration anddescription only and is not intended as a definition of the limits ofthe present disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present disclosure, referenceis now made to the following descriptions taken in conjunction with theaccompanying drawings, in which:

FIG. 1 is a block diagram illustrating an example of a communicationssystem according to certain aspects of the present disclosure;

FIG. 2 is a block diagram illustrating a design of an AP and a UEconfigured according to one aspect of the present disclosure;

FIG. 3 is a functional block diagram illustrating example blocksexecuted to implement an aspect of the present disclosure; and

FIG. 4 is a block diagram representation of a wireless communicationapparatus configured according to an aspect of the present disclosure.

DETAILED DESCRIPTION OF THE DISCLOSURE

Systems and methods described herein obviate the limitation ofcommunicating under IEEE 802.11 standards (i.e., WiFi wirelesscommunication) by utilizing only carriers within particular sub-channelsor a contiguous combination of sub-channels. WiFi is a populartechnology that allows an electronic device to exchange data wirelessly(using radio waves) over a computer network, including high-speedInternet connections. The WiFi Alliance defines WiFi as any wirelesslocal area network (WLAN) products that are based on the Institute ofElectrical and Electronics Engineers' (IEEE) 802.11 standards. Accordingto concepts described herein, under, for example, the current IEEE802.11ac standard, a device may utilize a relatively wide channel, i.e.,160 MHz, for data transmission and reception and/or severalnon-contiguous sub-channels therein. That is, the channel may be dividedinto several sub-channels, e.g., eight (8) 20 MHz sub-channels, four (4)40 MHz sub-channels, or two (2) 80 MHz sub-channels. Current 802.11devices may be assigned or otherwise determine that several sub-channelsare available for communication. The devices may then aggregate or bondone or more available or assigned sub-channels to increase data rates.However, the devices are able to utilize carriers only within theassigned or available sub-channels, but are not able to utilize carriersfrom other sub-channels, e.g., unassigned sub-channels or sub-channelsthat have been determined to be low performing, low priority, orotherwise undesirable.

In a known 802.11 system, within the FORM physical (PHY) layer, thechannel bandwidth is 20 MHz The 802.11 n standard further providessupport for an optional 40 MHz channel and the 802.11ac standardprovides support for an 80 MHz channel as well as an optional 160 MHzchannel. A known 802.11ac device must support 20, 40, and 80 MHz channelbandwidth reception and transmission, where an 80 MHz channel willconsist of two adjacent, non-overlapping 40 MHz sub-channels, and a 160MHz channel will consist of two adjacent, non-overlapping 80 MHzsub-channels.

As such, channels according to, e.g., the 802.11ac or 802.11n standardsare treated with a spectrum channel block allocation so that eachchannel is incremented in multiple 20 MHz-wide sub-channels. Accordingto known systems, standards require that only contiguous 20 MHz bands becombined to create, e.g., 40 MHz-wide or 80 MHz-wide sub-channels(according to the 802.11n & 802.11ac standards) or a 160 MHz-widechannel under the 802.11ac standard. According to those standards, OFDMsubcarriers are spaced from one another at 312.5 kHz. Accordingly, in aknown 802.11ac system, 20 MHz-wide contiguous channels, e.g.,sub-channels 1-4, are combined to form a single 80 MHz wide channel.However, this is problematic in the case of interference across one ormore sub-channels. For example, the WiFi band centered about the 5 cGHzband shares channels with Radar, and if Radar interference is detected,a user is required to suspend WiFi communication in the sub-channeloccupied by Radar interference. In this example where Radar interferenceoccupied sub-channel 3, using, e.g., dynamic frequency selection (DFS),a user would be limited to using only sub-channels 1 and 2.

According to concepts described herein, following the previous example,a user would be able to utilize sub-channels 1, 2, and 4, and in somecases, subcarriers within sub-channel 3, where such subcarriers are notoccupied by the interfering Radar signal. According to an embodiment,this is accomplished by “notching out” specific OFDM subcarriers at,e.g., 312.5 kHz subcarrier increments. Extended further, the entireband, including sub-channels 1, 2, 3, and 4 may be examined to create achannel map—where only individual interfering 312.5 kHz subcarriers arenotched out to create the map. Extended even further, considering theprevious example, the user could examine multiple WiFi bands across,e.g., the 2.4 GHz communication band and the 5 GHz communication bandand treat the intermediate, interfering subcarriers as the “knocked out”subcarriers.

According to additional concepts described herein, an IEEE 802.11 devicemay utilize carriers across the entire available spectrum, even inotherwise low priority or undesirable sub-channels. In doing so, an IEEE802.11 device utilizes an ultra-wideband tuner to evaluate the entireavailable spectrum between several communication bands (e.g., the 2.4GHz and 5 GHz bands), and then take advantage of the OFDM protocol tocancel interference on a carrier-by-carrier or cluster-by-cluster basis.

One or more Access Points (“APs”) communicate with one another and/orwith one or more User Equipment (“UEs”). The APs and UEs may communicatein a multi-communication band, multi-carrier wireless network. Ratherthan being constrained to communicate in a single communication band,the APs and UEs may utilize more than one communication band tocommunicate with one another. In doing so, the AP and UE searchacross 1) available bands (e.g., the 2.4 GHz, 5 GHZ, and/or 60 GHzbands), and 2) sub-channels within each band, and measure interferenceon a carrier-by-carrier basis across those bands and sub-channels.Either of the AP and UE may select a cluster of carriers forcommunication, where the cluster of carriers may comprise: 1) contiguouscarriers in a single sub-channel, 2) contiguous carriers spanning acrossmore than one sub-channel, 3) discontinuous carriers in a singlesub-channel, or 4) discontinuous carriers spanning across more than onesub-channel. The sub-channels that support a cluster may be within asingle communication channel or contained in more than one communicationchannels. A cluster comprising consecutive or contiguous carriers may bereferred to as a coherence cluster, while a cluster comprising disjointor discontinuous carriers may be referred to as a diversity cluster. Themapping between a cluster and its carriers can be fixed orreconfigurable. The APs and/or UEs perform interference mitigation on acarrier-by-carrier basis to allow optimized communications, evenutilizing multiple bands.

FIG. 1 illustrates a wireless communication network 100, which may be awireless local area network (WLAN). Preferred embodiments of the presentdisclosure are directed to devices communicating under the IEEE 802.11standards, and are meant to relieve network burden from particularlyhigh traffic density in those environments. Wireless network 100includes a number of wireless network APs 110 and other networkentities. An AP may be a station that communicates with other APs and/orUEs and may also be referred to as a node and the like. Each AP 110 mayprovide communication coverage for a particular “hot spot,” typicallyhaving a range of about 20 meters (65 feet) indoors and a greater rangeoutdoors. In the example shown in FIG. 1, the APs 110 a, 110 b, and 110c serve hotspots 102 a, 102 b and 102 c, respectively. The AP 110 dserves hotspot 102 d, the APs 110 e and 110 f serve hotspots 102 e and102 f, respectively.

Within network 100, each AP may further communicate with one or moreeNodeBs. An eNodeB may provide communication coverage for a macro cell,a pico cell, a femtocell, a small cell, and/or other types of cell. AneNodeB may support one or multiple (e.g., two, three, four, and thelike) cells. A macro cell generally covers a relatively large geographicarea (e.g., several kilometers in radius) and may allow unrestrictedaccess by UEs with service subscriptions with the network provider. Apico cell generally covers a relatively smaller geographic area and mayallow unrestricted access by UEs with service subscriptions with thenetwork provider. A femtocell generally covers a relatively smallgeographic area in a residential-type setting (e.g., a home or smallbusiness) and, in addition to unrestricted access, may also providerestricted access by UEs having an association with the femtocell (e.g.,UEs in a closed UE group (CSG), UEs for users in the home, and thelike). A small cell covers a relatively small geographic area in anurban-type setting (e.g., a shopping mall, enterprise area, etc.) andmay provide unrestricted access and restricted access by UEs having anassociation with the small cell. Finally, an eNodeB for a macro cell maybe referred to as a macro eNodeB, an eNodeB for a pico cell may bereferred to as a pico eNodeB, an eNodeB for a femtocell may be referredto as a femto eNodeB or a home eNodeB, and an eNodeB for a small cellmay be referred to as a small cell eNodeB.

A network controller 130 may couple to a set of APs 110 and providecoordination and control for these APs 110. The network controller 130may communicate with the APs 110 via a backhaul or via one or more ofthe eNodeBs described above.

UEs 120 are dispersed throughout the wireless network 100, and each UEmay be stationary or mobile. A UE may also be referred to as a terminal,a mobile station, a UE unit, a station, or the like. A UE may be acellular phone, a personal digital assistant (PDA), a wireless modem, awireless communication device, a handheld device, a laptop computer, acordless phone, a wireless local loop (WLL) station, a tablet, or thelike. A UE may be able to communicate with macro eNodeBs, pico eNodeBs,small cell eNodeBs, relays, and the like. In FIG. 1, a solid line withdouble arrows indicates desired transmissions between a UE and a servingAP, which is an AP designated to serve the UE on the downlink and/oruplink. A dashed line with double arrows indicates interferingtransmissions between a UE and an AP.

FIG. 2 is a block diagram of a design of a AP 110 and a UE 120, whichmay be one of the APs and one of the UEs in FIG. 1. The AP 110 may beequipped with antennas 234 a through 234 t, and the UE 120 may beequipped with antennas 252 a through 252 r.

At AP 110, a transmit processor 220 may receive data from a data source212 and control information from a controller/processor 240. Theprocessor 220 may process (e.g., encode and symbol map) the data andcontrol information to obtain data symbols and control symbols,respectively. The processor 220 may also generate reference symbols andhotspot-specific reference signals. A transmit (TX) multiple-inputmultiple-output (MIMO) processor 230 may perform spatial processing(e.g., precoding) on the data symbols, the control symbols, and/or thereference symbols, if applicable, and may provide output symbol streamsto the modulators (MODs) 232 a through 232 t. Each modulator 232 mayprocess a respective output symbol stream (e.g., for OFDM, etc.) toobtain an output sample stream. Each modulator 232 may further process(e.g., convert to analog, amplify, filter, and upconvert) the outputsample stream to obtain a downlink signal. Downlink signals frommodulators 232 a through 232 t may be transmitted via the antennas 234 athrough 234 t, respectively.

At UE 120, the antennas 252 a through 252 r may receive the downlinksignals from the AP 110 and may provide received signals to thedemodulators (DEMODs) 254 a through 254 r, respectively. Eachdemodulator 254 may condition (e.g., filter, amplify, downconvert, anddigitize) a respective received signal to obtain input samples. Eachdemodulator 254 may further process the input samples (e.g., for OFDM,etc.) to obtain received symbols. A MIMO detector 256 may obtainreceived symbols from all the demodulators 254 a through 254 r, performMIMO detection on the received symbols if applicable, and providedetected symbols. A receive processor 258 may process (e.g., demodulate,deinterleave, and decode) the detected symbols, provide decoded data forthe UE 120 to a data sink 260, and provide decoded control informationto a controller/processor 280.

On the uplink, at the UE 120, a transmit processor 264 may receive andprocess data from a data source 262 and control information from thecontroller/processor 280. The processor 264 may also generate referencesymbols for a reference signal. The symbols from the transmit processor264 may be precoded by a TX MIMO processor 266 if applicable, furtherprocessed by the modulators 254 a through 254 r, and transmitted to theAP 110. At AP 110, the uplink signals from the UE 120 may be received bythe antennas 234, processed by the demodulators 232, detected by a MIMOdetector 236 if applicable, and further processed by a receive processor238 to obtain decoded data and control information sent by the UE 120.The processor 238 may provide the decoded data to a data sink 239 andthe decoded control information to the controller/processor 240.

The controllers/processors 240 and 280 may direct the operation at theAP 110 and the UE 120, respectively. The processor 240 and/or otherprocessors and modules at the AP 110 may perform or direct the executionof various processes for the techniques described herein. The processor280 and/or other processors and modules at the UE 120 may also performor direct the execution of the functional blocks relating to APs and/orother processes for the techniques described herein. The memories 242and 282 may store data and program codes for the AP 110 and the UE 120,respectively. A scheduler 244 may schedule UEs for data transmission onthe downlink and/or uplink.

An AP, such as AP 110 e, communicates with a UE, such as UE 120 e, overmore than one communication band utilizing IEEE 802.11 standards.Transmit processor 220 and receive processor 238 are designed in amanner so that they process signals over various communication bands. Indoing so, the AP and UE provide additional network capacity whileavoiding undue burden on a particular communication band. The AP mayfurther utilize frequency bands for both the uplink (UL) and downlink(DL), e.g., shared by UL and DL according to FDD or TDD communicationschemes. According to one aspect, controller/processor 240 of AP 110 eis programmed in a manner such that the frequency band that will be usedto modulate signals transmitted by antennas 234 can be selectedautomatically or manually by a system operator.

Generally, as employed herein, unless otherwise noted, a communicationband (sometime referred to as a “frequency band”) is a generallycontiguous portion of the electromagnetic spectrum which is regulated bya governmental entity, such as the Federal Communications Commission(FCC) for the United States, generally under a single designation.According to an aspect of the present disclosure, an AP and UEcommunicate with one another under the IEEE 802.11 standards utilizingone or more communication bands. Examples of bands used by the AP and UEinclude bands such as those centered upon or about 2.4 GHz, 5 GHz, and60 GHz. As such, the AP and UE may communicate as IEEE 802.11ac devices,802.11n devices, 802.11ad devices, and the like.

For example, according to certain aspects, under the IEEE 802.11acstandard, an AP and UE utilize one or more 160 MHz channels within aband, where the channels may be divided into several sub-channels, e.g.,eight (8) 20 MHz sub-channels, four (4) 40 MHz sub-channels, or two (2)80 MHz sub-channels. The devices may then aggregate one or moreavailable assigned sub-channels to increase data rates. further, thedevices are able to utilize carriers across the entire band, e.g.,carriers from unassigned sub-channels or sub-channels that have beendetermined to be low performing, low priority, or otherwise undesirable.

Decisions to initiate, maintain, and/or alternate communication oncertain carriers or clusters of carriers can be made at both the AP andthe UE. These decisions may be based upon different metrics or qualities(such as CQI, SNR, etc.) of respective carriers or clusters of carriersmeasured at either of the AP and/or UE. Further, each AP and UE maydevelop a priority of preferred carriers or clusters of carriers. Inthis way, APs may communicate with one or more UEs on utilizing morethan one band or multiple sub-channels across more than one band in anoptimal way.

Each AP and UE may perform one or a combination of steps to avoid ormitigate interference from devices communicating on to-be-selected orpreviously-selected carriers or a cluster of carriers. Interferencemitigation may be performed by the AP and/or the UE on acarrier-by-carrier basis or a cluster-by-cluster basis across more thanone band. It should be appreciate that interference mitigation on acarrier-by-carrier basis or a cluster-by-cluster basis may beaccomplished utilizing different techniques. According to oneembodiment, subcarriers spaced from one another at, e.g., 312.5 KHz, areexamined to identify interference levels on each subcarrier. This isperformed on each subcarrier, irrespective of which particularsub-channel or communication band (e.g., the 2.4 GHz or 5 GHz band) thesubcarrier belongs. Where interference is determined (by way ofmeasurement or evaluation) to be too high or above a threshold amount,the subcarriers suffering an unduly high amount of interference may be“notched out” on a carrier-by-carrier basis. Further, a channel map maycreate for carriers across sub-channels and across communication bandsso that a user can select subcarriers from across those bands to form acluster for communication. As such, the user is not constrained to asingle sub-channel or contiguous sub-channels.

Preferably, techniques utilized herein proactively reject and mitigateinterference on specific carriers. If performance throughput degradesdue to interference or other environmental conditions, an AP and/or UEmay determine an optimum antenna combination to, e.g., avoid problematiccarriers. One available technique involves selecting carriers acrossmultiple sub-channels, where those carriers are determined to beunder-utilized utilizing using the Carrier Sense Multiple Access (CSMA)protocol. In this way, the overall quality of a given sub-channel may betreated as a secondary consideration, where a primary consideration isto avoid Wi-Fi collisions. That is, a trade off may be made on acarrier-by-carrier basis to avoid collisions even where the carriersselected for use are within an otherwise undesirable or less preferredsub-channel.

Further, the AP and/or UE may perform a “monitor” function on one ormore of the available carriers to determine which, if any, are moresuitable. The monitor function may comprise monitoring one or morecarriers or clusters of carriers, across multiple bands, to determinewhat devices are utilizing those carriers, whether any communication isperiodic or aperiodic, and the strength of interference on thosecarriers. Further, the monitor function may be performed aperiodically,periodically (e.g., according to a preset interval or according tooperator or system preferences), or continuously (where, e.g., theincreased power requirements are justified by the extra bandwidthfeatures). Further, the AP and/or UE may detect interference on one ormore carriers, determine whether the detected interference is periodicor aperiodic, and then schedule communications on optimal carriers toavoid the interference. On the other hand, the AP and/or UE may increasetransmit power if interference on carriers cannot effectively beavoided. Additionally, the AP and/or UE select specific carriers thatmay be scheduled for communication during other device transmissiongaps, similar to a TDD scheme, to allow other devices to operate one thecarriers.

Each AP or UE may continuously monitor the reception of pilot symbolsand measure the SINR and/or other parameters, including inter-hotspotinterference and intra-hotspot interference, of each cluster. Based onthat information, each AP or UE selects one or more clusters with goodperformance (e.g., high SINR and low traffic loading) relative to eachother and feeds back the information on these candidate clusters to theeNodeB through predefined uplink access channels. For example, SINRvalues higher than 10 dB may indicate good performance. Likewise, acluster utilization factor less than 50% may be indicative of goodperformance. Each AP or UE selects the clusters with relatively betterperformance than others. The selection results in each AP or UEselecting clusters they would prefer to use based on the measuredparameters.

In one embodiment, each UE measures the SINR of each carrier cluster andreports these SINR measurements to an AP through an access channel. TheSINR value may comprise the average of the SINR values of each of thecarriers in the cluster. Alternatively, the SINR value for the clustermay be the worst SINR among the SINR values of the carriers in thecluster. In still another embodiment, a weighted averaging of SINRvalues of the carriers in the cluster is used to generate an SINR valuefor the cluster. This may be particularly useful in diversity clusterswhere the weighting applied to the carriers may be different.

The feedback of information from each UE to the AP contains a SINR valuefor each cluster and also indicates the coding/modulation rate that theUE desires to use. No cluster index is needed to indicate which SINRvalue in the feedback corresponds to which cluster as long as the orderof information in the feedback is known to the AP. In an alternativeembodiment, the information in the feedback is ordered according towhich clusters have the best performance relative to each other for theUE. In such a case, an index is needed to indicate to which cluster theaccompanying SINR value corresponds.

Upon receiving the feedback from a UE, the AP further selects one ormore clusters for the UE among the candidates. The AP may utilizeadditional information available at the AP, e.g., the traffic loadinformation on each carrier, amount of traffic requests queued at the APfor each frequency band, whether frequency bands are overused, and howlong a UE has been waiting to send information. The carrier loadinginformation of neighboring cells can also be exchanged between APs. TheAPs can use this information in carrier allocation to reduce inter-cellinterference.

After cluster selection, the AP notifies the UE about the clusterallocation through a downlink common control channel or through adedicated downlink traffic channel if the connection to the UE hasalready been established. In one embodiment, the AP also informs the UEabout the appropriate modulation/coding rates.

Once the basic communication link is established, each UE can continueto send the feedback to the AP using a dedicated traffic channel (e.g.,one or more predefined uplink access channels). However, the trafficchannel may include a diversity cluster, which itself may includedisjoint carriers across one or more communication bands.

In one embodiment, the AP allocates all the clusters to be used by a UEat once. In an alternative embodiment, the AP first allocates multipleclusters, referred to herein as the basic clusters, to establish a datalink between the AP and the UE. The AP then subsequently allocates moreclusters, referred to herein as the auxiliary clusters, to the UE toincrease the communication bandwidth. Higher priorities can be given tothe assignment of basic clusters and lower priorities may be given tothat of auxiliary clusters. For example, the AP first ensures theassignment of the basic clusters to the UEs and then tries to satisfyfurther requests on the auxiliary clusters from the UEs. Alternatively,the AP may assign auxiliary clusters to one or more UEs beforeallocating basic clusters to other UEs. For example, a AP may allocatebasic and auxiliary clusters to one UE before allocating any clusters toother UEs. In one embodiment, the AP allocates basic clusters to a newUE and then determines if there are any other UEs requesting clusters.If not, then the AP allocates the auxiliary clusters to that new UE.

Further, on downlink channels, each UE may measure the channel andinterference information for all the carriers and then select multiplecarriers with good performance (e.g., a high signal-to-interference plusnoise ratio (SINR)) and feedback the information on these candidatecarriers to the AP. The feedback may comprise channel and interferenceinformation (e.g., signal-to-interference-plus-noise-ratio information)on all carriers or just a portion of carriers. In case of providinginformation on only a portion of the carriers, a UE may provide a listof carriers ordered starting with those carriers which the UE desires touse, usually because their performance is good or better than that ofother carriers. Upon receiving the information from the UE, the APfurther selects the carriers among the candidates, utilizing additionalinformation available at the AP, e.g., the traffic load information oneach carrier, amount of traffic requests queued at the AP for eachfrequency band, whether frequency bands are overused, and/or how long aUE has been waiting to send information. In one embodiment, the carrierloading information of neighboring cells can also be exchanged betweenAPs. The APs can use this information in carrier allocation to reduceinter-cell interference.

According to other aspects, the decision making and allocationprocedures previously described as performed by one or more APs may beadditionally or alternatively performed by one or more UEs. According toyet other aspects, a separate device such as a controller may beutilized to coordinate communication between the AP and UE and otherdevices operating on the same bands. The controller may be implementedat, e.g., the AP or the core network, and may obtain device and channelinformation from the AP, UE, external network devices operating onvarious communication bands, and the like. In this way, the AP isconnected to the controller, which allocates and manages the spectrumutilization across multiple communication bands.

A rank or priority of carriers or clusters of carriers may be compiledsuch that the AP and/or UE optimize their communications when decidingto utilize specific carriers or clusters of carriers. Further, suchsteps may be repeated so that the carriers or clusters of carriers arere-prioritized over time to further inform the AP, UE, or controller ofan optimal carriers or clusters of carriers for communication atsubsequent times.

According to concepts described herein, interference can be cancelled ona carrier-by-carrier basis by utilizing a number of mechanisms,including adaptive nulling and deterministic nulling. In utilizingadaptive nulling, a receiver at an AP or UE identified the interferencecomponents within the received signals, and the signals from theantennas (or the cross products from pairs of antennas) are combined ina way that causes the interference vectors to cancel one another. Inutilizing deterministic nulling, the direction of the interferingtransmission source is identified and a null signal or vector is formedin that direction. Nulls can be formed by adjusting the weights withwhich the cross-products of the outputs of pairs of antennas arecombined. In this way, the nulls are formed in the synthesized beam.

With the previous discussion in mind, an exemplary system according tothe present discussion involves an IEEE 802.11 AP and a UE eachutilizing ultra wideband tuners for tuning to carriers across one ormore communication bands. As employed herein, an ultra-wideband tuner isone that is capable of tuning on the order of 1 GHz of frequency.Consider that the AP and UE are communicating according to a standard,such as, e.g., the 802.11n or 802.11ac standard. In that situation, theAP and UE may center their tuners upon a given center frequency, suchas, e.g., the 2.4 GHz or 5 GHz band. Further, each communication channelmay be divided into multiple sub-channels, e.g., four (4) 40 MHzsub-channels or eight (8) 20 MHz sub-channels. By exploiting the OFDMprotocol and ultra wideband tuners, the AP and UE may scan over one orboth of the 2.4 GHz band and the 5 GHz band to identify available oreven desirable sub-channels. Further, however, the devices may selectfrom all sub-channels to identify what carriers or groups of carriersare optimal. Once identified, a cluster of carriers can be utilized forcommunication, even where the cluster comprise carriers fromsub-channels in both the 2.4 GHz band and the 5 GHz band.

Accordingly, consider that a device utilizes a channel in a firstcommunication band (e.g., the communication band center about 2.4 GHz),which is divided into eight sub-channels (i.e., sub-channels 1, 2, 3, 4,5, 6, 7, and 8) and a channel in a second communication band (e.g., thecommunication band center about 5 GHz), which is divided into eightsub-channels (i.e., sub-channels 9, 10, 11, 12, 13, 14, 15, 16, 17, and18). Whereas it may have previously been determined that one or moresub-channels are unavailable, e.g., where a sub-channel is determined togenerally subject to low SINR, high traffic, etc. Previousimplementations would have excluded the undesirable sub-channel in itsentirety. However, according to the concepts described herein,adequately performing carriers within the generally undesirablesub-channel can be identified and utilized by the AP and UE to form acluster for communication there between.

FIG. 3 is a functional block diagram 300 illustrating example blocksexecuted to implement aspects of the present disclosure. At block 301,an AP such as AP 110 or a UE such as UE 120 shown in FIG. 1, operatingwithin a cellular network searches across a plurality of communicationbands to determine interference levels in each of said pluralitycommunication bands. The AP or UE is able to do so by utilizing anultra-wideband tuner, which allows the AP or UE to search across theorder of 1 GHz of frequency. The AP or UE measures interference on acarrier-by-carriers basis or a cluster-by-cluster basis. In doing so,the AP or UE may additionally measure interference levels for varioussub-channels within a given communication band. The communication bandsof interest may be disjointed, i.e., where one band of interest isseparated from another band of interest by a substantial bandwidth. Inany event, particular communication bands of interest may include theband centered about 2.4 GHz and 5 GHz.

At block 302, based on the determination or measurement of interferencelevels performed at block 301, a first set of carriers are identifiedfor communication. These carriers may be thought of as candidatecarriers, which are expect to qualify as those carriers most likely toprovide optimized communications between an AP and UE. The first set ofcarriers may be thought of as a cluster of carriers, and maycomprise: 1) contiguous carriers in a single sub-channel, 2) contiguouscarriers spanning across more than one sub-channel, 3) discontinuouscarriers in a single sub-channel, or 4) discontinuous carriers spanningacross more than one sub-channel. Further, given sub-channels withineach sub-channel may be identified as sub-channels having a higher orlower number of candidate carriers. As part of this process, the AP orUE may rank or prioritize the carriers, clusters, or sub-channelsaccording to their respective measured interference levels. By way ofexample, sub-channels having a relatively high number of candidatecarriers may quality as a higher priority sub-channel while those havinga relatively low number of candidate carriers may quality as a lowerpriority sub-channel. The rank or priority may be transmitted to anothercommunication apparatus, such as an AP or UE, or a controller, which mayfurther communicate same to the other communicating apparatus.

An AP or UE may transmit an indication of the identified carriers to anapparatus with which it is communicating. That is, where the AP or UEidentified candidate carriers or a set of carriers it prefers forcommunication, that information may be shared with the other apparatus.This serves to inform the other apparatus that it should take stepsnecessary to 1) confirm those candidate carriers as acceptable forcommunication, and 2), if so, prepare to communication using thecandidate carriers. Doing so may involve tuning to the appropriatecarriers, performing steps to route other inter-cell and intra-celltraffic away from those carriers, and set appropriate modulation andtiming schemes to avoid undue interference The other communicationapparatus may additionally transmit an acknowledgment to the AP or UEthat it agrees the candidate carriers are acceptable. Further, the othercommunication apparatus may take additional steps to refine thecandidate carriers by, e.g., communicating a new ranking or priority orsimply removing carriers its finds to be unacceptable.

At block 303, the AP or UE performs interference mitigation on acarrier-by-carrier basis for at least some of said identified carriersin each of said plurality of communication bands. The interferencemitigation may be performed in a number of ways including, e.g., theadaptive and deterministic nulling techniques described herein. In thisway, carriers within otherwise low priority or otherwise unqualifiedsub-channels may still be utilized for communications. That is, carrierswithin such otherwise low priority or otherwise unqualified sub-channelsmay utilized to form a set of carriers for which communications willoccur.

At block 304, the AP or UE transmits wireless data on the identified setof carriers. The AP or UE does so utilizing the appropriate interferencemitigation techniques described above at block 303.

At block 305, blocks 301-304 are performed at subsequent time intervalsas a mechanism to ensure that carriers used for communication areoptimal carriers. That is, a second search may be performed across thecommunication bands to determine interference levels on carriers atsubsequent times. Based on the measure interference levels at subsequenttimes, an updated set of candidate carriers may be created. As such,interference mitigation may be performed on the new set of candidatecarriers and the communicating devices will tune to the new carriers forcontinued communication.

FIG. 4 is a block diagram illustrating apparatus 400 for wirelesscommunication. Apparatus 400 may include one or more components orportions of small cell AP 110 or UE 120. Apparatus 400 also includesmodules 401, 402, 403, 404, and 405, which are executed to provideoperations as described herein. Each of modules 401, 402, 403, 404, and405 may comprise software, program code, or other logic (e.g., ASIC,FPGA, etc.), as may be operable upon or executed by processor 401 toprovide the functions described below.

Module 401 operates under control of a processor of apparatus 400 tosearch across a plurality of communication bands to determineinterference levels in each of said plurality communication bands.Apparatus 400 is able to do so by utilizing an ultra-wideband tuner,which allows it to search across the order of 1 GHz of frequency.Apparatus measures interference on a carrier-by-carriers basis or acluster-by-cluster basis. In doing so, apparatus 400 may additionallymeasure interference levels for various sub-channels within a givencommunication band. The communication bands of interest may bedisjointed, i.e., where one band of interest is separated from anotherband of interest by a substantial bandwidth. In any event, particularcommunication bands of interest may include the band centered about 2.4GHz and 5 GHz.

Module 402 operates under control of a processor of apparatus 400 to,based on the determination or measurement of interference levelsperformed by module 401, identify a first set of carriers forcommunication. These carriers may be thought of as candidate carriers,which are expect to qualify as those carriers most likely to provideoptimized communications between apparatus 400 and another communicatingapparatus, e.g., an AP 110 or UE 120. The first set of carriers may bethought of as a cluster of carriers, and may comprise: 1) contiguouscarriers in a single communication band, 2) contiguous carriers spanningacross more than one communication band, 3) discontinuous carriers in asingle communication band, or 4) discontinuous carriers spanning acrossmore than one communication band. Further, given sub-channels withineach communication band may be identified as sub-channels having ahigher or lower number of candidate carriers. As part of this process,apparatus 400 may rank or prioritize the carriers, clusters, orsub-channels according to their respective measured interference levels.By way of example, sub-channels having a relatively high number ofcandidate carriers may quality as a higher priority sub-channel whilethose having a relatively low number of candidate carriers may qualityas a lower priority sub-channel. The rank or priority may be transmittedto another communication apparatus, such as an AP 110 or UE 120, or acontroller, which may further communicate same to the othercommunicating apparatus.

Apparatus 400 may transmit an indication of the identified carriers toan apparatus with which it is communicating. That is, where apparatus400 identifies candidate carriers or a set of carriers it prefers forcommunication, that information may be shared with the other apparatus.This serves to inform the other communicating apparatus that it shouldtake steps necessary to 1) confirm those candidate carriers asacceptable for communication, and 2), if so, prepare to communicationusing the candidate carriers. Doing so may involve tuning to theappropriate carriers, performing steps to route other inter-cell andintra-cell traffic away from those carriers, and set appropriatemodulation and timing schemes to avoid undue interference. The othercommunication apparatus may additionally transmit an acknowledgment toapparatus 400 that it agrees the candidate carriers are acceptable.Further, the other communication apparatus may take additional steps torefine the candidate carriers by, e.g., communicating a new ranking orpriority or simply removing carriers its finds to be unacceptable.

Module 403 operates under control of a processor of apparatus 400 toperform interference mitigation on a carrier-by-carrier basis for atleast some of said identified carriers in each of said plurality ofcommunication bands. The interference mitigation may be performed in anumber of ways including, e.g., the adaptive and deterministic nullingtechniques described herein. In this way, carriers within otherwise lowpriority or otherwise unqualified sub-channels may still be utilized forcommunications. That is, carriers within such otherwise low priority orotherwise unqualified sub-channels may utilized to form a set ofcarriers for which communications will occur.

Module 404 operates under control of a processor of apparatus 400 totransmit wireless data on the identified set of carriers. Apparatus 400does so utilizing the appropriate interference mitigation techniquesperformed by module 403.

Module 405 operates under control of a processor of apparatus 400 toperform, at subsequent time intervals, subsequent steps to ensure thatcarriers used for communication are optimal carriers. That is, a secondsearch may be performed across the communication bands to determineinterference levels on carriers at subsequent times. Based on themeasured interference levels at subsequent times, an updated set ofcandidate carriers may be created. As such, interference mitigation maybe performed on the new set of candidate carriers and the communicatingdevices will tune to the new carriers for continued communication.

Those of skill in the art would understand that information and signalsmay be represented using any of a variety of different technologies andtechniques. For example, data, instructions, commands, information,signals, bits, symbols, and chips that may be referenced throughout theabove description may be represented by voltages, currents,electromagnetic waves, magnetic fields or particles, optical fields orparticles, or any combination thereof.

Those of skill would further appreciate that the various illustrativelogical blocks, modules, circuits, and algorithm steps described inconnection with the disclosure herein may be implemented as electronichardware, computer software, or combinations of both. To clearlyillustrate this interchangeability of hardware and software, variousillustrative components, blocks, modules, circuits, and steps have beendescribed above generally in terms of their functionality. Whether suchfunctionality is implemented as hardware or software depends upon theparticular application and design constraints imposed on the overallsystem. Skilled artisans may implement the described functionality invarying ways for each particular application, but such implementationdecisions should not be interpreted as causing a departure from thescope of the present disclosure.

The various illustrative logical blocks, modules, and circuits describedin connection with the disclosure herein may be implemented or performedwith a general-purpose processor, a digital signal processor (DSP), anapplication specific integrated circuit (ASIC), a field programmablegate array (FPGA) or other programmable logic device, discrete gate ortransistor logic, discrete hardware components, or any combinationthereof designed to perform the functions described herein. Ageneral-purpose processor may be a microprocessor, but in thealternative, the processor may be any conventional processor,controller, microcontroller, or state machine. A processor may also beimplemented as a combination of computing devices, e.g., a combinationof a DSP and a microprocessor, a plurality of microprocessors, one ormore microprocessors in conjunction with a DSP core, or any other suchconfiguration.

The steps of a method or algorithm described in connection with thedisclosure herein may be embodied directly in hardware, in a softwaremodule executed by a processor, or in a combination of the two. Asoftware module may reside in RAM memory, flash memory, ROM memory,EPROM memory, EEPROM memory, registers, hard disk, a removable disk, aCD-ROM, or any other form of storage medium known in the art. Anexemplary storage medium is coupled to the processor such that theprocessor can read information from, and write information to, thestorage medium. In the alternative, the storage medium may be integralto the processor. The processor and the storage medium may reside in anASIC. The ASIC may reside in a user terminal. In the alternative, theprocessor and the storage medium may reside as discrete components in auser terminal.

In one or more exemplary designs, the functions described may beimplemented in hardware, software, firmware, or any combination thereof.If implemented in software, the functions may be stored on ortransmitted over as one or more instructions or code on acomputer-readable medium. Computer-readable media includes both computerstorage media and communication media including any medium thatfacilitates transfer of a computer program from one place to another. Astorage media may be any available media that can be accessed by ageneral purpose or special purpose computer. By way of example, and notlimitation, such computer-readable media can comprise RAM, ROM, EEPROM,CD-ROM or other optical disk storage, magnetic disk storage or othermagnetic storage devices, or any other medium that can be used to carryor store desired program code means in the form of instructions or datastructures and that can be accessed by a general-purpose orspecial-purpose computer, or a general-purpose or special-purposeprocessor. Also, disk and disc, as used herein, includes compact disc(CD), laser disc, optical disc, digital versatile disc (DVD), floppydisk and blu-ray disc where disks usually reproduce data magnetically,while discs reproduce data optically with lasers. Combinations of theabove should also be included within the scope of computer-readablemedia.

The previous description of the disclosure is provided to enable anyperson skilled in the art to make or use the disclosure. Variousmodifications to the disclosure will be readily apparent to thoseskilled in the art, and the generic principles defined herein may beapplied to other variations without departing from the spirit or scopeof the disclosure. Thus, the disclosure is not intended to be limited tothe examples and designs described herein but is to be accorded thewidest scope consistent with the principles and novel features disclosedherein.

What is claimed is:
 1. A method for wireless communication in amulti-band, multi-carrier wireless network, said method comprising:searching across a plurality of (IEEE) 802.11 communication bands todetermine interference levels in each of said plurality (IEEE) 802.11communication bands; based on said determination of interference levelsin each of said plurality (IEEE) 802.11 communication bands, identifyingcarriers in each of said bands for communication; mitigatinginterference on a carrier-by-carrier basis for at least some of saididentified carriers in each of said plurality of (IEEE) 802.11communication bands; and transmitting wireless data on said carriers ineach of said (IEEE) 802.11 communication bands utilizing said mitigationinterference.
 2. The method of claim 1 further comprising: transmittingan indication of said identified carriers to a User Equipment (UE); andin response to said transmitting, receiving an acknowledgment of saididentified carriers from said UE.
 3. The method of claim 1 furthercomprising: transmitting an indication of said identified carriers to anAccess Point (AP); and in response to said transmitting, receiving anacknowledgment of said identified carriers from said AP.
 4. The methodof claim 1 wherein said mitigating interference comprises: identifyinginterference components in said identified carriers; and combining saidinterference components in a way that causes said interferencecomponents to cancel one another.
 5. The method of claim 1 wherein saidmitigating interference comprises: identifying a direction from whichinterference components in said identified carriers are received; andtransmitting a null signal in said direction.
 6. The method of claim 1further comprising: performing a second search across said plurality of(IEEE) 802.11 communication bands to determine second interferencelevels in each of said plurality (IEEE) 802.11 communication bands;based on said determination of said second interference levels in eachof said plurality (IEEE) 802.11 communication bands, identifying asecond set of carriers in each of said bands for communication;mitigating interference on a carrier-by-carrier basis for at least someof said identified second set of carriers in each of said plurality of(IEEE) 802.11 communication bands; and transmitting wireless data onsaid second set of carriers in each of said (IEEE) 802.11 communicationbands utilizing said mitigation interference.
 7. The method of claim 1wherein a first of said plurality of (IEEE) 802.11 communication bandsis a (IEEE) 802.11 communication band centered about 2.4 GHz.
 8. Themethod of claim 1 wherein a second of said plurality of (IEEE) 802.11communication bands is a (IEEE) 802.11 communication band centered about5 GHz.
 9. An apparatus configured for wireless communication in amulti-band, multi-carrier wireless network, said apparatus comprising:at least one processor; and a memory coupled to said at least oneprocessor, wherein the said least one processor is configured to: searchacross a plurality of (IEEE) 802.11 communication bands to determineinterference levels in each of said plurality (IEEE) 802.11communication bands; based on said determination of interference levelsin each of said plurality (IEEE) 802.11 communication bands, identify aset of carriers in each of said bands for communication; mitigateinterference on a carrier-by-carrier basis for at least some of saididentified carriers in each of said plurality of (IEEE) 802.11communication bands; and transmit wireless data on said carriers in eachof said (IEEE) 802.11 communication bands utilizing said mitigationinterference.
 10. The apparatus of claim 9 wherein said processor isfurther configured to: transmit an indication of said identifiedcarriers to a UE; and in response to said transmitting, receive anacknowledgment of said identified carriers from said UE.
 11. Theapparatus of claim 9 wherein said processor is further configured to:transmit an indication of said identified carriers to an eNodeB; and inresponse to said transmitting, receive an acknowledgment of saididentified carriers from said eNodeB.
 12. The apparatus of claim 9wherein said processor is further configured to: identify interferencecomponents in said identified carriers; and combine said interferencecomponents in a way that causes said interference components to cancelone another.
 13. The apparatus of claim 9 wherein said processor isfurther configured to: identify a direction from which interferencecomponents in said identified carriers are received; and transmit a nullsignal in said direction.
 14. The apparatus of claim 9 wherein saidprocessor is further configured to: perform a second search across saidplurality of (IEEE) 802.11 communication bands to determine secondinterference levels in each of said plurality (IEEE) 802.11communication bands; based on said determination of said secondinterference levels in each of said plurality (IEEE) 802.11communication bands, identify a second set of carriers in each of saidbands for communication; mitigate interference on a carrier-by-carrierbasis for at least some of said identified second set of carriers ineach of said plurality of (IEEE) 802.11 communication bands; andtransmit wireless data on said second set of carriers in each of said(IEEE) 802.11 communication bands utilizing said mitigationinterference.
 15. The apparatus of claim 9 wherein said processor isfurther configured to: tune said apparatus to a (IEEE) 802.11communication band centered about 2.4.GHz.
 16. The apparatus of claim 9wherein said processor is further configured to: tune said apparatus toa (IEEE) 802.11 communication band centered about 5 GHz.